3.1. Asymmetry in skull shape in dorsal and ventral view analyses respectively
Procrustes ANOVA demonstrated (Table 1) that in both dorsal and ventral view analyses the results are highly repeatable (F=10.5501 and 4.1967, P=0.0001) for dorsal and ventral views respectively as between sides variation values are larger than within sides variation (measurement error) contributions (F=0.00034755 and 0.0024199, P= -) respectively in the same order. FA accounted for 61.77% and 72.01% of variations in dorsal and ventral cranium, respectively and was not found significant (p˂0), signal noise for dorsal view was observed significantly high (F=0.00034755) and comparable to values for FA (ns) and could not be employed for further analysis.
A regression model of log transformed centroid size and asymmetric components suggested the significant expression of asymmetry throughout ontogeny (p˂0.03) and that size accounted for 81.34% of asymmetric shape changes of this component. Further, a multivariate analysis of regression confirmed DA and a low significance (p˂0.5) of fluctuating asymmetry (FA) (F1539=3.4045, F882= 3.2665) for dorsal and ventral views (Table 2). More shape changes concentrated collectively more on the rostro-dorsal and caudal areas and were right side biased (Fig. 4a and b) suggestive of a low association between environment and skull development in Small Pangolins to justify observed skull asymmetries (hypothesis 1).
Intraspecific allometric ontogenetic trajectories among samples under assessment suggested a rostro-caudal followed by a caudo-lateral growth trajectory considering the intercepts for shape versus size predictions (Fig. 5) was found parallel. Intercept (-4.43), slope (-11.168) p˂0.0004 while overall statistics R2= 0.013, Wilk’s Lambda=1.07E-11, df-21, 7, F=3.091E 10, p˂0.0001. in a pooled sample population across geographical locations.
Figure 4a, b and c Grid representation of PCA implied deformation for directional asymmetry, (b) Implied deformation for individual side interaction (FA) for dorsal skull views ( Mag X 10) (c) Regression model of log transformed centroid size (CS) versus asymmetric components of data in P. tricuspis